U.S. Pat. No. 5,935,039 discloses a non-finite speed ratio transmission device which combines a toroidal continuously variable transmission, a fixed speed ratio transmission and a planetary gear unit in order to obtain a speed ratio range larger than the toroidal continuously variable transmission. Tokkai Hei 10-267117 published by the Japanese Patent Office in 1997 discloses a controller which controls the creep torque applied to a drive wheel at low vehicle speed according to the operating state of the brake in such an non-finite speed ratio transmission device.
This controller assigns a step number obtained by subtracting or adding a fixed amount from a step number corresponding to a geared neutral position GNP to a step motor, and increases or decreases a difference of oil pressure acting on a trunnion from two directions using a relief valve.
The geared neutral position GNP is a rotating position of the step motor at which the output rotation speed of the non-finite speed ratio transmission device becomes zero.